# Auth (/auth)



## Automatic by default [#automatic-by-default]

A project needs secure sign-in before real users can depend on it. Crucible configures Auth, callback URLs, and project access from the start, and most teams build the product instead of maintaining a login system.

* **[Project members](/iam/)**: Add or remove people in the project's **Users** tab. Crucible keeps their sign-in access in sync with their project roles.
* **Sign-in users**: Use **User Access** to invite people who use the product but do not manage it in Crucible. [Auth sandboxes](/auth-sandboxes/) keeps test identities separate from production.